This image shows the Duke of Edinburgh in his capacity as Captain General Royal Marines. Note that his rank slide has the royal cypher of his father-in-law George VI; the Duke was a personal aide-de-camp to the king and is thus entitled to wear the cypher.

I was wondering how many men or women capable of putting on a uniform would these days wear that cypher. (George VI died in 1952 - more than 65 years ago.)